Troy Bilt 5000/6250w Generator runs fine but trips circuit breaker

[SABEStef]

I have a Troy Bilt 5000w/6250w Generator with a B&S 1450 Series Engine that runs fine but trips the circuit breaker after approx 1-2 minutes even without a load on the generator; engine continues to run fine. When attempting to use generator power circuit breaker consistently trips. When attempting to trouble shoot the problem I removed (unplugged) all electrical loads from the generator and circuit breaker still trips continuously after approximately 1-2 minutes. The generator has approximately 24 hours of run since bought new approximately 3 years ago with no problems until now. Checked all ground connections and wiring with no visible evidence of problem areas. Any suggestions?